One common form of a heat exchanger includes a so-called "core" made up of tubes and interconnecting fins. One heat exchange fluid is passed through the tubes of the core while a second heat exchange fluid is passed through the core itself in the spaces between adjacent fins.
In the usual case, at opposite sides of the core, there are located inlet and outlet "tanks" or manifolds. The tanks are in fluid communication with the interior of the tubes and arranged so that some desired flow path through the tubes is achieved.
Heat exchangers of this general sort may be used for a large variety of purposes. A typical use is as a radiator in a vehicle which serves to cool coolant for the engine. In the usual case, the vehicle coolant system will be operating at a relatively low pressure allowing the use of thin walled tubes in the core with an ultimate consequence that compactness of the core is relatively easily achieved. Where, however, heat exchangers of the general sort described above are used in higher pressure applications as, for example, a condenser in a refrigeration system, thinned wall tubes of the sort useful in vehicular radiators are of insufficient strength to withstand the pressure of the compressed refrigerant directed to the condenser to condense therein. Consequently, in such uses, resort has been made to thicker walled tubes. In order to minimize the wall thickness and thus material requirements of such tubes, it has also been typical that such tubes have a circular cross section to provide increased hoop strength sufficient to withstand the pressures involved.
Further, in applications such as refrigerant condensers, it is frequently advantageous to provide for multiple passes of the tube bound fluid through the core. This in turn means that the tubes must emerge from one end of the core and be redirected through the core. In some instances, this has been accomplished through the use of 180.degree. elbows while in others it has been accomplished simply by bending the tube 180.degree..
In either event, a considerable radius in the elbow or the bend has been required to prevent kinking of the tube or otherwise restricting flow as the tube bound heat exchange fluid reverses its direction by 180.degree.. This, in turn, has required that the tubes that run through the core be spaced from one another a distance equal to approximately twice the radius of curvature of the elbow or the bend. The typical result is an increase in the depth of the core.
Increased core depths, depending upon a fin structure employed, may result in increased so-called "air side" pressure drop which will increase system energy requirements if the heat exchange fluid flowing through the core must be propelled therethrough by means of a fan or the like. Perhaps even more importantly, the increased core depth means that the total volume occupied by the heat exchanger will be proportionally increased; and in many applications, particularly in vehicles, the increased volume and accompanying increased weight simply cannot be tolerated
The present invention is directed to overcoming one or more of the above problems.